Why is water more unforgiving than land?

[LostElement]

It honestly doesn't make much sense to me. I was watching mythbusters and they tested wether landing on water is deadlier than land. They did 50ft to terminal velocity. The land obviously is deadlier than water. But in KSP it seems as though water = Death.

I could land at 12ms with my lander and suffer little to no damage. But on water everything just falls apart or explodes. Is it the KSP physics or am I missing something here?

[Aragosnat]

water = concreate at certain speeds

Basicly water does not compress easily as say dirt, sand or dust...

[LostElement]

I do not think so. According to Mythbusters water doesn't = concrete, even at terminal velocity. Concrete pulled 500+gs and water only pulled somewhere around 250 Gs

[EtherDragon]

water = concreate at certain speeds

Basicly water does not compress easily as say dirt, sand or dust...

This is actually a misconception. Water != Concrete at any speed. Water is incompressible, but it is also deformable - much more so than concrete, sand, and dirt. A fatal fall onto water occurs at higher velocities than onto concrete, sand, dirt, etc... Mind you, past a certain point fatal is fatal - but it's not because the water is acting like concrete - it's because water is acting like water, but you are moving so fast that the force delivered to your person while the water tries to move out of the way is enough to kill you.

As far as KSP is concerned - water landings are touchy because it depends on how submerged you end up. In KSP, generally any landing over 10m/s could be fatal depending on where and how you land - so just make sure you have sufficient parachutes to handle the load.

[AlamoVampire]

except water is UNCOMPRESSABLE. you hit it at a certain speed, and its going to rip you apart. period. oh, and the test that adam and jamie and the gang did, obliterated the pig they used. or at least thats what the xray showed after a water impact.

[Kasuha]

KSP water is not the same as water Mythbusters were testing.

The matter - probably - is that in KSP, parts have certain speed tolerance which is used when you crash into something. When you land on ground, only what touches the ground is checked for this value. When you land in water, every part which touches the water is checked for that. And since your landing legs won't stop the fall in water, large part of your ship goes through that.

When landing on water, make sure you touchdown at speed below the lowest speed tolerance of any parts you have on your ship.

[wasmic]

Easy solution: more chutes. If you're losing your spacecraft to a 12m/s landing, it's your own fault for landing irresponsibly fast.

[iNUKE]

As I said, it ALL depends on the shape of the object and the position of that object when landing.

Landing with one of the corners of your object should survive a lot better than landing flatened out straight.

It seems like this game doesnt count on that (if you hit the water with a corner of your ship or straight flat bottom)

Landing on water: Hit the corner first, should survive more speed.

This game doesnt count of if you hit the water with a corner or not, which is wrong but its a game.

[Dodgey]

With landing on land you have your landing legs to absorb the impact, if you land on water your landing legs go through the water and the rest of your craft is left to absorb the impact.

[Clockwork_werewolf]

With landing on land you have your landing legs to absorb the impact, if you land on water your landing legs go through the water and the rest of your craft is left to absorb the impact.

Exactly this. The PROBLEM is the water is softer, its sort of a KSP physics problem. You should be going slower than 12m/s though. I consider it a max of 10m/s and aim for 6 to 2m/s. Maybe even attach a couple of Sepratrons to it and fire them seconds before touchdown. At 18 thrust each a 7 ton craft would be slowed to half the decent speed (I think, unless the parachutes produce lift not drag). Turning 12m/s into 6 m/s.

[Epthelyn]

Exactly this. The PROBLEM is the water is softer, its sort of a KSP physics problem.

So in real life you can land on water without landing legs and other usually non-buoyant parts passing through it?

[Clockwork_werewolf]

So in real life you can land on water without landing legs and other usually non-buoyant parts passing through it?

Lol no in real life you have bouncy devices, you can adjust the size, shape, strength, hardness and purpose of the parts designed to land in the water without needing to glue new parts on and worrying about the capsule bending on the rubbery welding points. KSP is different to real life, this was just to explain the problem with KSP water landings.

[lajoswinkler]

If you hit the water at a certain angle and speed, it traps you. On ground, you just splat. It's easier to skid on ground. It all varies with the angle and the speed of descent.

And actually, water is compressible, but very little. If it weren't, the sea level above the deepest parts of the oceans would be around 20 metres higher.

[Brapness]

I think the case here is that water has the ability to be moved out of the way to some extent, whereas ground doesn't (at least not as much). There are a hundred other factors such as angle, speed, composition etc

I think its unforgiving in KSP because you enter it, whereupon an extremely strong drag and buoyant force is applied to your vessel, destroying it. That's a guess, I don't really know. But seriously, almost everything in KSP floats. How dense must that water be?

[Brotoro]

KSP water is not the same as water Mythbusters were testing.

The matter - probably - is that in KSP, parts have certain speed tolerance which is used when you crash into something. When you land on ground, only what touches the ground is checked for this value. When you land in water, every part which touches the water is checked for that. And since your landing legs won't stop the fall in water, large part of your ship goes through that.

When landing on water, make sure you touchdown at speed below the lowest speed tolerance of any parts you have on your ship.

Kashua is correct.

Also, a ship that can end up standing upright on the ground can end up falling over and breaking in the water even if you do land it slow enough.

[Dispatcher]

Beware the Water Kraken!

[Geschosskopf]

Here on earth, where are all the kraken sightings? In the water! That's why water is deadly.

HOWEVER, there is no water at all in KSP. There's stuff that looks like water but really isn't because it has radically different physical properties. As Pebbles amply demonstrated in this "To the Bottom of the OCEAN!" thread, even neutronium would float in Kerbin's oceans. Whatever makes up these oceans, it's definitely NOT water.

And now we know why there are no clouds on Kerbin, nor tides, nor waves. The liquid is too dense to move, too heavy to evaporate. And that's a good thing, because rain on Kerbin would immediately sledgehammer all the mountains flat and pulverize the continents into dust. So it's little wonder that objects that fall into Kerbin's oceans don't fair well.

[Dunbaratu]

except water is UNCOMPRESSABLE. you hit it at a certain speed, and its going to rip you apart. period. oh, and the test that adam and jamie and the gang did, obliterated the pig they used. or at least thats what the xray showed after a water impact.

The problem is that people are taking "water is not soft when you hit it at high speed" as meaning "water is harder than land when you hit it at high speed", which is bogus. It's harder than one would intuit, but not as hard as land is.

To prove it, you just show a comparison of at what speed certain effects occur for hitting land vs water. In real life, the same effect you get from hitting water at high speed you can get from hitting land at a lower speed. But that's not true in KSP. The question here is NOT "why is landing on water unforgiving in KSP", but "why is it MORE unforgiving than land?". That's the bit that doesn't make sense. in KSP, hitting land at 9 m/s is survivable. Hitting water at 9 m/s isn't.

This is my guess as to why it happens, but this is a guess:

   falling on its bottom into the water.
     |  |  |
     V  V  V

     /\
    /  \
^^^/____\^^^^^^^^^^^^^^ water line ^^^^
   |    |
   |____|  <-- These bits that dip beneath 
     /\        the water get destroyed by KSP.
    /__\


   falling on its side into the water.
     |  |  |
     V  V  V
    ____ _____
   /    |    | /|
^^/^^^^^|^^^^|^^|^^^^^^ water line ^^^^
  \     |    |- |
   \____|____| \|   <-- none of the bits
                       dip beneath the water

Edited February 7, 2014 by Steven Mading

[Dunbaratu]

Easy solution: more chutes. If you're losing your spacecraft to a 12m/s landing, it's your own fault for landing irresponsibly fast.

No, that is not a solution, because the question wasn't "how do I make my craft survive despite this weird behavior?". The question was about why the weird behavior is the way it is in the first place.

[Alchemist]

One of the things with KSP water is that it probably doesn't apply force of impact.

When you impact land you get some impulse that very moment even if the bottom part is destroyed. So you can smash everything except your pod and get your speed reduced by that to survivable levels. The water seem to apply drag and buoyancy to the parts moving in it, but if something just blows up by impact it doesn't slow the rest down. And because you can't just absorb all the impact by the legs (with real water they wouldn't help too) it's a high chance to smash your entire craft tank by tank.

You can land a heavy craft in water without damage or turning over. It just has to be short and wide and use engines to soften splashdown. Proven by Laythe-grade landers.

[Superfluous J]

The problem is the ridiculous way KSP handles the "Should this part explode due to impact?" question. The answer is based entirely on how fast it's going when it hits something.

If you have a 400,000 ton space station and drop it ON AN EXTENDED ANTENNA at less than 7 meters per second, it will balance ON THAT ANTENNA with no problems, until it falls to the side. If you drop just the antenna (which would probably, on its own, survive most any fall in a real-world setting) so it hits the ground all by itself at more than 7 meters per second, it will explode on impact. Take the exact same space station and put a girder where the antenna is, and suddenly your entire space station can hit the ground at up to 80 meters per second and not explode.

Hitting the ground causes whatever hits the ground to slow your craft significantly, and then that part explodes. Then the next part of your craft hits the ground at a lesser velocity and (if that velocity is high enough) IT explodes. Continue this until you either run out of parts (and your craft has fully exploded) or you slow down enough to not destroy parts any more.

In a water landing, the exact same thing happens but the slowdown is a lot less and parts hitting the water don't stop moving. Therefore, higher-up parts get a chance to explode on impact than on land. Therefore, you lose a lot more parts.

For simplicity, I'm ignoring deformation of the craft due to sudden deceleration. It exists but in most situations it's a small enough factor to not matter.

Edited February 7, 2014 by 5thHorseman

[TimePeriod]

Instead of more boosters, MORE PARACHUTES!

[boxman]

If i recall correctly the current water physics were meant to be nothing more than a placeholder and is currently way to dense compared to in real life. This is why it is so destructive even at low velocities.

I also bet that this is the reason why it is so hard to make "boats" that go fast as well.

I really hope that is one of the things they will fix eventually.

Edited February 7, 2014 by boxman

[Kasuha]

I wouldn't talk about water density here. I have no idea how part buoyancy is calculated but I strongly doubt any real notion of density has anything to do with it.

[Dunbaratu]

I wouldn't talk about water density here. I have no idea how part buoyancy is calculated but I strongly doubt any real notion of density has anything to do with it.

Especially since *EVERY* part in KSP floats, no matter what it is. A metal girder shouldn't float. In KSP it does.